On Tue, 13 Jun 2000 15:22:39 -0500, Bob Hughes wrote:
>"Peter J. Holzer" <hjp### [at] SiKituwsracat> wrote in message
>news:slr### [at] tealhhjpat...
>|
>| While playing around with superellipsoids and the orthographic camera
>| I found that the superellipsoid vanishes if the camera is pointing
>| exactly along the X axis.
[...]
>|
>| So it looks like the ray->shape Intersection test for superellipsoids
>| doesn't work if the ray is exactly parallel to the x axis.
>
>Really makes me wonder what's going on behind the scenes (heh, a
>pun) anyway. If the slight offset of x or z from 0 is done and
>'orthographic' is placed first ahead of anything else then the
>superellipsoid more than fills the display window. When placed after
>'location' and before 'angle' it shows up but only as a tiny size.

Yes, this is normal and documented. Angle is ignored if it comes after
the orthographic keyword, and look_at works somewhat differently. This
may be a little bit surprising at first, but its rather logical and you
get used to it. That's not my problem.


>However the s.e. is still non-existant it seems otherwise. Also, unless
>the axes are offset a fair amount, say <90,1,1> there are artifacts
>showing up at the shadow/light boundary, perspective camera or not.

You are right. I didn't notice them at first, because my test rendering
was only 320x240. But at 1024x768 they are very clearly visible. They
look similar to the artifacts one gets with coincident surfaces, so I
guess that's also a ray/shape intersection test problem (maybe the ray
misses the front surface and hits the back surface?)

	hp

-- 
   _  | Peter J. Holzer    | Nicht an Tueren mangelt es,
|_|_) | Sysadmin WSR       | sondern an der Einrichtung (aka Content).
| |   | hjp### [at] wsracat      |    -- Ale### [at] univieacat
__/   | http://www.hjp.at/ |       zum Thema Portale in at.linux

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